Add last use data flow information to the fast code generator....

src/fast-codegen.cc

Index: src/fast-codegen.cc
===================================================================
--- src/fast-codegen.cc	(revision 3827)
+++ src/fast-codegen.cc	(working copy)
@@ -428,6 +428,9 @@
   AstLabeler labeler;
   labeler.Label(info);
 
+  LivenessAnalyzer analyzer;
+  analyzer.Analyze(info->function());
+
   CodeGenerator::MakeCodePrologue(info);
 
   const int kInitialBufferSize = 4 * KB;
@@ -584,7 +587,8 @@
     Comment cmnt(masm(), ";; Global");
     if (FLAG_print_ir) {
       SmartPointer<char> name = expr->name()->ToCString();
-      PrintF("%d: t%d = Global(%s)\n", expr->num(), expr->num(), *name);
+      PrintF("%d: t%d = Global(%s)  // last_use = %d\n", expr->num(),
+             expr->num(), *name, expr->var_def()->last_use()->num());
     }
     EmitGlobalVariableLoad(cell);
   }
@@ -638,7 +642,9 @@
     SmartPointer<char> name_string = name->ToCString();
     PrintF("%d: ", expr->num());
     if (!destination().is(no_reg)) PrintF("t%d = ", expr->num());
-    PrintF("Store(this, \"%s\", t%d)\n", *name_string, expr->value()->num());
+    PrintF("Store(this, \"%s\", t%d)  // last_use(this) = %d\n", *name_string,
+           expr->value()->num(),
+           expr->var_def()->last_use()->num());
   }
 
   EmitThisPropertyStore(name);
@@ -661,8 +667,9 @@
     Comment cmnt(masm(), ";; Load from this");
     if (FLAG_print_ir) {
       SmartPointer<char> name_string = name->ToCString();
-      PrintF("%d: t%d = Load(this, \"%s\")\n",
-             expr->num(), expr->num(), *name_string);
+      PrintF("%d: t%d = Load(this, \"%s\")  // last_use(this) = %d\n",
+             expr->num(), expr->num(), *name_string,
+             expr->var_def()->last_use()->num());
     }
     EmitThisPropertyLoad(name);
   }